Federal Reserve Bank, Charlotte, NC

GreenWise
Green roofs create marketing value for your building and organization, which can lead to higher rents and increased resale value.

FAQ

A healthy green roof is a living system that is changing and adapting. A green roof will continue to be sustainable if it receives these minimal inputs (which could actually come from nature). In terms of appearance, the field should be 80 percent to 90 percent covered with plants proven to survive that microclimate. There should never be ponding water on the surface of the system. A healthy green roof will also go through periods of dormancy throughout, so don't expect the same scene every time you visit the rooftop. Lastly, in determining the sustainability of a roof, evaluate the entire field — don't focus on each and every individual plant. The living roof creates its own ecology. Keep in mind, some German green roofs are more than 100 years old. That's sustainable!
Green roofs are mentioned as a potential technology in several points. In the real world, they can easily achieve 2-3 points, although others claim their value is much more than that.
Temperate climates are best, but more extreme climates like Florida and Arizona have started to see a rise in installations. Our facility in Orlando, for example, installed about 5 this year alone.
Yes, within reason. Natives must be selected based on local and microclimate conditions, including watering requirements and maintenance needs. Warranties may be an issue, so be sure to communicate with all parties involved what the expectations are. We have completed and maintain several green roofs including Minneapolis City Hall, and Target Center, with varying success of native species.
Call a qualified roofer to core the roof and evaluate the viability of the system. A report on the dead load of the structure is also required.
Typically, a well maintained extensive green roof will never be a fire hazard. The aggregate soils will not easily burn, and the plant material is lush. If there is an irrigation system, that could be used to prevent fire, as well.
Easily 50-100% There is a lot of statistically analyzed storm water research from accredited universities across the country that provide an unbias opinion on the stormwater benefits.
It should if it has been designed, installed, and maintained properly. The exact amount varies on a project basis. Your energy savings goals should be discussed during the planning process so that your green roof can be designed and installed according to your expectations.
Most of our projects reach 80% within 1 year.
NO! Only if you are authorized to be on the roof and maintaining it. However, there are many roofs designed for public safety you can visit if you are being escorted by a professional.
Slightly more than a gravel ballast roof, or paver system- about 17-20 lbs. per square foot at the minimum.
Watering during the early stages is usually a requirement. Long term use of irrigation should only be needed if there is a unique plant pallet with high watering requirements. Cisterns are commonly being added to projects for irrigation needs.
Those involved should include: the building owner, single source installer, and facility manager. A consultant or designer may need to be involved as well.
You want to install the growing media one time on a roof to avoid high yearly maintenance. Growing media is specially blended to sustain life on a rooftop.
A traditional green roof system is built right onto the rooftop in an intricate system of layers. A continuous green roof is usually more flexible in design, utilizing walkways or detailing around roof penetrations. Typically, there is 12 percent to 16 percent greater storm-water holding capacity in a continuous system. A modular system can be pre-planted or assembled on-site and applied over the top of an already-existing rooftop structure. There are different types of modular systems, and these answers may vary per manufacturer, but generally a modular system can be used on sites where craning soil may be difficult or expensive and may be more economical in smaller projects, such as terraces or in residential applications. These systems allow you the option of moving vegetation patterns around the roofscape and allow easier removal to access the roof membrane if necessary. Both systems use drought-tolerant plants, usually succulents, and lightweight growing media.
In general, temporary irrigation should be available for at least the first couple months, and it should saturate the system at least two or three times weekly. Thereafter, irrigation should be weaned, with the intent that the vegetation will remain self-sustaining within the first year. Additionally, the growing media should be evaluated to ensure proper drainage. A slow-release fertilizer should be used in the spring with critical periodic weeding in the summer.

Have a question? Ask our Green Roof Professionals at greenroofexperts@tectaamerica.com.